Collector and separator apparatus for lawn and garden

ABSTRACT

An apparatus for collection and reduction of yard debris combining a frontally facing rotor-assisted vacuum pick up with a chipper-shredder-blower unit to induce airflow for entraining debris collected at the vacuum pick up; reduce the entrained debris to a more manageable volume; and impel the reduced debris to a free-flow-separator device for removing the debris from the air in which it is entrained.

FIELD OF THE INVENTION

This application is a division of and claims priority of theearlier-filed application having Ser. No. 10/045,123 filed on Nov. 9,2001, now U.S. Pat. No. 6,658,833 which claims the benefit ofProvisional Application No. 60/247,456, filed Nov. 9, 2000. Thisapplication also relates to continuation-in-part application Ser. No.10/846,029, now U.S. Pat. No. 6,904,742 B2, and to divisionalapplication Ser. No. 11/145,289 filed Jun. 3, 2005. This inventionapplies to an apparatus for collection and reduction of yard debris inthick layers and deep piles.

BACKGROUND

Homeowners, commercial-property owners, and companies who provide carefor lawns have an ongoing challenge of how to remove leaves, grassclippings, and other debris from lawns, gardens and paved surfaces,particularly when the debris accumulates to a depth of over an inch.Several companies now manufacture and sell combinationvacuum-chipper-shredder machines intended for this purpose. Some U.S.patents illustrating the range of these machines are as follows: U.S.Pat. Nos. 5,931,396 and 5,799,365, both assigned to MTD Products; U.S.Pat. Nos. 5,381,970 and 5,231,827, both assigned to Garden WayIncorporated; and U.S. Pat. No. 5,642,864, assigned to SimplicityManufacturing, Inc. However, the dilemma with many prior-art units isthat while they are reasonably adapted to vacuum a thin layer of debrisfrom the ground, they do not function well when there is a thick layerof leaves or other debris. When there is a covering of several inches ofleaves, the collector duct merely pushes a stack of leaves ahead of theunit instead of drawing the leaves into the machine. If the collectorduct is raised to be able to take leaves from the top of the overlayer,it is no longer so effective in collecting the leaves and other debrisclose to the ground. Accordingly, while the available machines aresomewhat effective in removing the thin layers of debris, the task ofcollecting thick layers of debris, particularly deep piles of leaves,remains quite problematic. Typical prior art machines, such as thoseshown in U.S. Pat. Nos. 5,799,365 and 5,231,827, have a vacuum pick-upopening wherein the plane of the opening is parallel to the ground,while the device shown in U.S. Pat. No. 5,642,864 has its openingdisposed at an angle of about 45 degrees with respect to the ground.Such devices are poorly adapted to the tasks for which machineassistance is needed most.

Many existing machines depend primarily on flow of air to lift andentrain the leaves and other debris for transport through chippershredder devices, and then to blow the reduced debris into accumulationunits. To separate the debris from the air in which it is entrained, themachines rely on some form of filtration, with either fabric bags orscreens. However, as leaf fragments and other debris collect on thefilter, resistance to the flow of air increases, diminishing the airflow rate, and thereby, reducing the effectiveness of the vacuum pick-upopening.

OBJECT OF THE INVENTION

It is an object of the present invention to provide a machine whicheffectively removes deep piles of leaves and other debris. In preferredembodiments, the thin layer of residual debris which might otherwise beleft for later removal in another step is cleanly removed at the sametime.

Another object of the invention is to provide a unit combining afront-facing vacuum-assisted opening with a rotor which serves to impelheavy leaves and debris toward a vacuum slot while creating air flowclose to the surface to be cleaned in a direction which is generallyparallel to that surface for picking up finer debris.

Another object of the invention is to provide a rotor-vacuum combinationwhich both frontally engages piles of leaves and other debris and alsobrushes the leaves and other debris from the surface to be cleaned whileentraining the debris in an air stream whence the debris may be reducedin size.

Another object of the invention is to provide a means for separating theair stream with entrained debris into a solids-depleted stream and asolids-enriched stream for collection and disposition of the debris.

It is another object of the present invention to remove deep piles ofleaves and other debris.

SUMMARY OF THE INVENTION

These objects are provided by an apparatus for collection and reductionof yard debris comprising a combination of a frontally facingrotor-assisted vacuum pick up, a chipper-shredder-blower unit which (i)induces an airflow for entraining the debris collected at said pick up;(ii) reduces the debris entrained in the airflow to a more manageablevolume and (iii) impels the reduced debris to a free-flow-separatordevice for removing the debris from the air in which it is entrained.

More particularly, this invention relates to an apparatus for collectingyard debris comprising: a frame having a shredder blower unit mountedthereupon; a collector-rotor mounted on the frame comprising impellerelements adapted to: (i) engage a surface, (ii) collect yard debristhereupon, and (iii) impel the yard debris toward the shredder blowerunit; an air-solids separator mounted on the frame operatively connectedto the shredder blower unit for separating the yard debris into adebris-enriched stream and a debris-depleted stream by action of bodyforces thereupon; and an accumulation chamber adapted to receive thedebris-enriched stream from the air-solids separator; wherein thecollector rotor means is configured for substantially untrammeledengagement with yard debris having a depth of at least about two (2)inches.

In another aspect this invention relates to an apparatus for collectingyard debris comprising: a frame; a shredder blower unit mounted on theframe; a collector rotor mounted on the frame comprising impellerelements adapted to: (i) engage a surface, collect yard debristhereupon, and (ii) impel said the debris toward the shredder blowerunit; an air-solids separator mounted on the frame operatively connectedto the shredder blower unit for separating the yard debris into adebris-enriched stream and a debris-depleted stream; and an accumulationchamber adapted to receive the debris-enriched stream from theair-solids separator; wherein the collector rotor is configured forsubstantially untrammeled engagement with yard debris having a depth ofat least about two (2) inches.

In still another aspect this invention relates to an apparatus forcollecting yard debris comprising: (A) a frame; (B) a shredder blowerunit mounted on the frame; (C) a collector rotor mounted on the framecomprising impeller elements adapted to: (i) engage a surface, collectyard debris thereupon, and (ii) impel the yard debris toward theshredder blower unit; (D) an air-solids separator means mounted on theframe operatively connected to the shredder blower unit for separatingthe yard debris into a debris-enriched stream and a debris-depletedstream by action of body forces thereupon; and (E) an accumulationchamber adapted to receive the debris-enriched stream from theair-solids separator.

Yet another aspect of this invention relates to an apparatus forcollecting and reducing yard debris comprising: (A) a frame adapted formovement in a principal direction upon a surface; (B) a first ductmounted on the frame having an entrance and an exit; (C) a collectorrotor assembly comprising: a collector rotor body disposed at theentrance to the first duct having a substantially horizontal axis ofrotation generally normal to the principal direction; and a plurality ofimpeller elements mounted upon the collector rotor body, wherein theimpeller elements extend radially from the collector rotor body by atleast about one quarter of an inch and are adapted to: (i) sweep overthe surface, (ii) collect yard debris thereupon, and (iii) impel theyard debris toward the duct entrance, wherein the collector rotorassembly and the first duct are configured for substantially untrammeledfrontal engagement with yard debris having a depth of at least about two(2) inches; (D) a second duct mounted upon the frame having an entranceand an exit; (E) a shredder blower unit, disposed between the exit tothe first duct and the entrance to the second duct, adapted to: (i)provide suction at the entrance of the first duct; (ii) induce a flow ofair through the first and second ducts; and (iii) reduce yard debrisentrained in the flow of air as it passes through the shredder blowerunit; (F) an air-solids separator disposed at the exit to the secondduct for separating the reduced yard debris in the flow of air inducedby the shredder blower into a debris-enriched stream and adebris-depleted stream; (G) an accumulation chamber mounted on the frameadapted to receive the debris-enriched stream from the air-solidsseparator; and (H) a power source mounted on the frame adapted toprovide power to the shredder blower unit and the collector rotor.

In a preferred embodiment of the invention the impeller elements extendradially at least about an inch from the collector rotor body.

In another preferred embodiment the collector rotor assembly comprises asubstantially gas-impervious impediment to unrestricted flow of air intothe first duct and extends substantially athwart the entrance to thefirst duct.

A preferred collector rotor assembly comprises three impeller elementsgenerally equispaced around the collector rotor body.

A more preferred collector rotor assembly further comprises filletsextending between adjacent impeller elements for limiting carriage ofyard debris around the collector rotor assembly, wherein the filletspartially define generally concentric interrupted annular cavity spacesbetween adjacent impeller elements.

In a more preferred embodiment of this invention, a housing serves tolimit the flow of air between the housing and the collector rotorassembly without substantially impeding air flow along the surface underthe collector rotor assembly and into the entrance of the first duct;wherein this housing: (i) is disposed above the collector rotorassembly, (ii) is an arcuate portion of a generally cylindrical shellspanning an upper portion of the collector rotor assembly concentric tothe axis of rotation of the collector rotor body, and (iii) engages eachof the impeller element tips in flow-limiting proximity seriatim.

In another preferred embodiment, vertically extending seals are carriedon the frame adjacent to the ends of the collector rotor assembly forlimiting axial flow of airflow into the rotor assembly.

In another embodiment, vertically extending seals carried on the ends ofthe collector rotor assembly limit axial flow of airflow into the rotorassembly.

In a preferred embodiment, the housing means defines a frontal openingextending from the surface vertically to a height of at least fourinches and a suction opening under the rotor extending rearwardly fromthe front of the apparatus at least to a line below the axis of rotationof the collector rotor body.

In another preferred embodiment, the impeller elements mounted on thecollector rotor body are configured to allow intermittent rearwardrushes of air under the forward side of the rotating rotor body into theentrance to the first duct, and pulsed forward rushes of air under thefirst duct and into the first duct entrance, thereby alternatinglycollecting principally bulky yard debris from the forward side of therotor body during the rearward rushes of air and enhancing collection ofresidual debris from the surface during the pulsed forward rushes ofair.

A preferred embodiment of the invention further comprises an air-slotdefined within the housing between the upper lip of the housing and theentrance to the first duct for allowing flow of air in a directionopposed to the direction of rotation of the collector rotor body andinto the first duct and therein stripping leaves and debris from therotating rotor assembly.

In another embodiment, the entrance to the first duct generally spansthe length of the collector rotor body, and the duct convergesrearwardly such that the convergence angle throughout the duct isgenerally less than 100 degrees.

In one embodiment, the shredder blower unit comprises a rotatable shafthaving shredder elements mounted thereupon, wherein the axis of rotationof the shaft is parallel to the principal direction.

In a preferred embodiment of the invention, the air-solids separatorcomprises: (A) a first passage for accepting the flow of air bearingentrained reduced yard debris from the second duct; (B) a separationchamber adapted to receive the flow of air from the first passage; (C) asecond passage adapted to exhaust the debris-depleted stream from theseparation chamber into the atmosphere; and (D) a baffle for: (i)generally inhibiting secondary flow from the accumulation chamber; and(ii) impeding re-entrainment of fine particulates in the debris-depletedstream as it is discharged to the atmosphere; wherein the baffle isdisposed to permit passage of entrained reduced yard debris into theaccumulation chamber while impeding passage of fine particulates ofreduced yard debris in air exhausted from the separation chamber throughthe second passage.

In a more preferred embodiment, the air-solids separator separates thereduced yard debris in the airflow induced by the shredder blower into adebris-enriched stream and a debris-depleted stream by action of bodyforces thereupon, wherein the separator comprises: (A) a separationchamber; (B) a first declivously extending curvilinear passage forconducting the flow of air bearing the entrained reduced yard debrisfrom the second duct into the separation chamber, wherein the separationchamber adjoins the declivously extending curvilinear passage and isadapted to receive and direct the flow of air bearing debris from thedeclivously extending curvilinear passage in a direction generallytangential to the perimeter of the separation chamber; (C) a generallycentrally located upwardly extending second passage for exhausting thedebris-depleted stream from the separation chamber into the atmosphere;(D) a baffle extending generally outwardly from a central point belowthe entrance to the second passage, wherein the baffle is disposedgenerally below the exit from the declivously extending curvilinearfirst passage; and (E) an opening around the baffle into theaccumulation chamber; wherein the baffle is disposed to permit passageof entrained reduced yard debris in the debris-enriched stream into theaccumulation chamber while impeding secondary flows of air containingfinely reduced debris fragments from re-entering the separation chamber.

In an embodiment, the shredder blower unit further comprises a chipperknife adapted to chip branches.

In another embodiment, the power source further comprises a means forsupplying power to wheels mounted on the frame, thereby powering forwardmovement of the apparatus.

In one embodiment, the air-solids separator means further comprises anenclosure having at least one filtering element, and the airflow passesthrough the filtering element, leaving the yard debris retained in theenclosure.

Another aspect of the invention relates to an apparatus for collectingyard debris comprising: (A) a frame adapted for movement in a principaldirection upon a surface; (B) a duct mounted on the frame having anentrance and an exit; (C) a collector rotor assembly comprising: asubstantially impervious collector rotor body disposed and extendingsubstantially athwart the entrance to the duct and having asubstantially horizontal axis of rotation generally normal to the firstdirection; and a plurality of impeller elements mounted upon thecollector rotor body, extending radially from the collector rotor bodyby at least about one quarter of an inch, and having approximately equalradial extensions from the axis of rotation of the collector rotorassembly, wherein the impeller elements are adapted to: (i) sweep overthe surface, (ii) collect yard debris thereupon, and (iii) impel theyard debris into the duct entrance; (D) a housing disposed adjacent theentrance to the duct for limiting the flow of air between the housingand the collector rotor assembly without substantially impeding air flowalong the surface under the collector rotor assembly and into theentrance of the duct, wherein the housing: (i) is disposed above thecollector rotor assembly; (ii) engages each of the impeller element tipsin flow-limiting proximity seriatim; and (iii) is configured to permitsubstantially untrammeled frontal engagement of the collector rotorassembly with yard debris having a depth of at least about two (2)inches; (E) an air-movement device connected to the exit of the duct andadapted to: (i) provide suction at the entrance of the duct, and (ii)induce a flow of air through the duct; and (F) a power source mountedupon the frame adapted to provide power to the air-movement device andthe collector rotor.

In a preferred embodiment of the invention, the tips of the impellersfurther comprise pliable blades that are yieldable to hard objectsencountered on the surface, but are sufficiently stiff to sweep debrisfrom the undulating surface.

In a more preferred embodiment, the tips of the impellers compriseradially extending raker teeth adapted to engage and impel debrisobjects on the surface toward the duct entrance.

In a further embodiment, the housing comprises an arcuate portion of agenerally cylindrical shell spanning an upper portion of the collectorrotor assembly generally concentric to the axis of rotation of thecollector rotor body, and which is disposed in flow-limiting proximityto at least one tip of one of the impeller elements during at leastabout one fourth of the time of each revolution of the collector rotorassembly.

In an embodiment, the duct is disposed such that a space at least ½ inchthick is preserved between the bottom of the duct and the surface,permitting forward air flow toward the duct entrance.

In a preferred embodiment, the cross-sectional area of the channelthrough the duct measured normal to the center flow line of the airflowthrough the duct remains generally constant along the center flow line.

In a further embodiment, the collector rotor assembly and the entranceof the duct are disposed along the advancing front of a lawnmower havinga cutting path of a defined width.

In a preferred embodiment, the collector rotor assembly impels the yarddebris into the mowing chamber within the mowing enclosure of thelawnmower.

In a more preferred embodiment, the air-movement means achieves anairflow volume of at least about twenty cubic feet per minute per inchof collector rotor assembly length.

In another preferred embodiment the present invention relates to anapparatus for separating entrained lawn debris from a transporting airstream by action of body forces thereupon comprising: (A) an apparatusfor delivering a stream of air bearing entrained lawn debris; (B) afirst passage having an entrance and exit, having the entrance adaptedto receive the stream of air bearing entrained lawn debris, and thepassage adapted for conducting the flow of air bearing entrained lawndebris from the entrance to the exit; (C) a separation chamber having agenerally cylindrical outer wall section, with the separation chamber:(i) connected to the exit from the first passage; and (ii) adapted to:(a) receive and direct the stream of air bearing entrained lawn debrisfrom the first passage in a direction primarily tangential to thegenerally cylindrical outer wall section of the separation chamber, and(b) separate the stream of air bearing entrained lawn debris into anouterly located debris-enriched stream and an innerly locateddebris-depleted stream; (D) an upper bulkhead to the separation chamberhaving defined therein, a generally centrally located second passagehaving an entrance and an exit, with the generally centrally locatedsecond passage adapted for: (i) receiving the innerly locateddebris-depleted stream from the separation chamber through the entrance,and (ii) conducting the innerly located debris-depleted stream to theexit and discharging it into the atmosphere; (E) the bulkhead of saidseparation chamber further: (i) extending generally horizontally fromthe second passage generally outwardly to the substantially cylindricalouter wall, and (ii) being disposed at generally the same height as theentrance to the second passage; (F) a baffle extending generallyoutwardly from a central point below the entrance to the second passage,wherein the baffle is disposed generally below the exit of the firstpassage, and the outer periphery of the baffle is spaced inwardly fromthe generally cylindrical outer wall section; and (G) an opening aroundthe baffle into the interior of an accumulation chamber below thebaffle; wherein the baffle is disposed to permit passage of entrainedyard debris into the accumulation chamber while impeding passage of fineparticulates of reduced yard debris from the accumulation chamber intothe debris-depleted stream discharged from the separation chamberthrough the second passage.

Preferably, the plane of the said baffle periphery is disposed below thelowermost portion of the upper bulkhead by a distance of less than about0.6 times the inside diameter of the separation chamber.

In another preferred embodiment, the baffle periphery is disposed belowthe lowermost portion of the entrance to the second passage by adistance of less than about 0.6 times the inside diameter of theseparation chamber.

In one embodiment the upper bulkhead of the separation chamber furthercomprises a substantially planar surface generally normal to the axis ofthe substantially cylindrical outer wall and has an opening comprisingthe entrance of the second passage.

In another embodiment, the upper bulkhead of the separation chamberfurther comprises a generally semi-toroidal surface and has an openingcomprising the entrance of the second passage.

Preferably, the upper bulkhead has as its substantially onlyinterruptions, openings comprising the exit of the first passage and theentrance of the second passage.

In a more preferred embodiment, the first passage extends declivouslyfrom its entrance toward its exit and directs the stream of air bearingentrained lawn debris into the separation chamber.

Preferably, (A) the first passage is curvilinear in a plane generallyperpendicular to the axis of the generally cylindrical outer wallsection, (B) the outer wall of the curvilinear passage is disposedapproximately coincident with the generally cylindrical outer wallsection of the separation chamber, and (C) the generally cylindricalouter wall section of the separation chamber is disposed at least aboutthree inches outward from the perimeter of the entrance to the secondpassage.

In a preferred embodiment, the generally cylindrical outer wall sectionof the separation chamber is disposed at least about five inchesoutwardly from the perimeter of the entrance to the second passage.

In a preferred embodiment, the baffle further comprises an upright conehaving its apex pointing toward the entrance of the second passage.

Preferably, the cone periphery and the outer wall section of theseparation chamber are generally circular.

In a preferred embodiment, the opening around the periphery furthercomprises an annular opening between the periphery of the baffle and theouter wall section of the separation chamber.

Preferably, the vertical distance from the apex of the cone to the planeof the entrance of the second passage is less than about 0.6 times thediameter of the entrance to the second passage.

In one embodiment, the accumulation chamber is approximately cylindricaland has a slidable opening in a plane at an angle of about 75 degrees toabout 90 degrees to the axis of the cylinder.

In a preferred embodiment, the stream of air bearing entrained lawndebris swirls around the separation chamber with a tangential perimetervelocity of at least about 2000 feet per minute, causing the entrainedreduced lawn debris to move toward the generally cylindrical outer wallof the separation chamber by action of body forces thereupon.

Preferably, the radial distance from the baffle periphery to the outerwall of the separation chamber is less than about one fourth of theinside diameter of the separation chamber, measured in approximately thesame plane as the plane of the baffle periphery.

In another embodiment, the accumulation chamber further comprises aflexible bag-like container, such as a paper bag or a plastic bag.

In still another embodiment, the device for delivering a stream of airbearing entrained lawn debris further comprises a lawnmower having adischarge duct connected to the entrance of the first passage.

In another aspect, this invention relates to a free-flow apparatus forseparating entrained lawn debris from a transporting air stream byaction of body forces thereupon comprising: (A) an apparatus fordelivering a stream of air bearing entrained lawn debris; (B) a firstpassage having an entrance and exit, with the entrance adapted toreceive the stream of air bearing entrained lawn debris, and the passageadapted for conducting the stream of air bearing entrained lawn debrisfrom the entrance to the exit; (C) a separation chamber having agenerally frusto-conical outer wall section, with the separationchamber: (a) connected to the exit from the first passage; and (b)adapted to: (i) receive and direct the stream of air bearing entrainedlawn debris from the first passage in a direction primarily tangentialto the frusto-conical outer wall section of the separation chamber, and(ii) separate the stream of air bearing entrained lawn debris into anouterly located debris-enriched stream and an innerly locateddebris-depleted stream; (D) a generally centrally located second passagehaving an entrance and an exit, and being adapted for (i) receiving theinnerly located debris-depleted stream from the separation chamberthrough the entrance, and (ii) conducting the innerly locateddebris-depleted stream to the exit and discharging it into theatmosphere; (E) an upper bulkhead to the separation chamber havingdefined therein a generally centrally located second passage having anentrance and an exit, with the upper bulkhead extending from the secondpassage generally outwardly to the generally frusto-conical outer wallsection; (F) a baffle extending generally outwardly from a central pointbelow the entrance to the second passage, and disposed generally belowthe exit of the first passage, wherein the outer periphery of the baffleis disposed inwardly from the generally frusto-conical outer wallsection, and below the uppermost portion of the first passage by adistance of less than 1.2 times the inside diameter of the separationchamber proximate the baffle; and (G) an opening around the baffle intothe interior of an accumulation chamber below the baffle; wherein thebaffle is disposed to permit passage of entrained yard debris into theaccumulation chamber while impeding passage of fine particulates ofreduced yard debris from the accumulation chamber into the airdischarged from the separation chamber through the second passage.

In a preferred embodiment, (A) the first passage is curvilinear in aplane generally perpendicular to the axis of the generally cylindricalouter wall, (B) the outer wall of the curvilinear passage is disposedgenerally coincident with the generally frusto-conical outer wallsection of said separation chamber, (C) the bulkhead is disposed atgenerally the same height as the entrance to the second passage, and (D)the generally frusto-conical outer wall section of the separationchamber is disposed at least about three inches radially outward fromthe perimeter of the entrance to the second passage.

Preferably, the first passage comprises substantially the only passagefor conducting air flow into the separation chamber, and the secondpassage comprises substantially the only passage for conducting theinnerly located debris-depleted stream out of the separation chamber.

In a preferred embodiment, the device for delivering a stream of airbearing entrained reduced lawn debris further comprises a shredderblower.

In another aspect, this invention relates to a free-flow apparatus forseparating entrained lawn debris from a transporting air stream byaction of body forces thereupon comprising: (A) an apparatus fordelivering a stream of air bearing entrained lawn debris; (B) aprimary-separation duct having an entrance and exit, wherein theentrance is adapted to receive the stream of air bearing entrained lawndebris, the duct is adapted for conducting the stream of air bearingentrained lawn debris from the entrance to the exit; and theprimary-separation duct has a generally curvilinear outer surfacespanning an arc of at least about

-   -   arc cosine(RI/RO)        circumferentially along its length, having the        primary-separation duct adapted to direct the stream of air        bearing entrained lawn debris to flow generally        circumferentially along its length and initiate separation of        the stream of air bearing entrained lawn debris into an outerly        located debris-enriched stream and an innerly located        debris-depleted stream, wherein    -   RI=radius of curvature for the generally curvilinear inner        surface of the primary-separation duct, and    -   RO=radius of curvature for the generally curvilinear outer        surface;        (C) a secondary-separation chamber connected to the exit from        the primary-separation duct and having a generally annular outer        wall defining a primary axis generally co-incident with the        center of curvature of the generally annular outer wall, the        functions of the secondary-separation chamber further        comprising (i) receiving and directing the streams of air        bearing entrained lawn debris from the primary-separation duct        in a direction generally tangential to the generally annular        outer wall of the secondary-separation chamber, (ii) directing        the outerly located debris-enhanced stream from the        primary-separation duct to flow adjacent to the outer wall of        the secondary-separation chamber, (iii) directing the innerly        located debris-depleted stream from the primary-separation duct        to flow radially inward of the debris-enriched stream, and (iv)        further separating the streams of air bearing entrained lawn        debris into an upwardly and inwardly directed debris-depleted        stream and a downwardly and outwardly directed debris-enriched        stream; (D) a generally centrally located passage having an        entrance and an exit, and being adapted for: (i) receiving the        upwardly and inwardly directed debris-depleted stream from the        secondary-separation chamber through the entrance, and (ii)        conducting this stream to the exit and discharging it into the        atmosphere; (E) a baffle extending generally outwardly from a        central point below the entrance to the passage, having the        outer periphery of the baffle spaced inwardly from the generally        annular outer wall; and (F) an opening around the baffle into        the interior of an accumulation chamber below the baffle;        wherein the baffle is disposed to permit passage of entrained        yard debris in the downwardly and outwardly directed        debris-enriched stream into the accumulation chamber while        impeding passage of fine particulates of reduced yard debris        from the accumulation chamber into air discharged from the        separation chamber through the passage.

Preferably, the baffle periphery is disposed below the uppermost portionof the primary-separation duct by a distance of less than 1.2 times theinside diameter of the secondary-separation chamber having a generallyannular outer wall, with this inside diameter being measured in theplane of the baffle periphery.

More preferably, the baffle periphery plane is disposed below theuppermost portion of the entrance to the passage by a distance of lessthan about 0.6 times the inside diameter of the secondary-separationchamber having a generally annular outer wall, with this inside diameterbeing measured in the plane of the baffle periphery.

In one embodiment, the axis of curvature of the primary-separation ductis disposed generally coincident with the primary axis.

Still another aspect of this invention relates to a free-flow apparatusfor separating entrained lawn debris from a transporting air stream byaction of body forces thereupon comprising: (A) an apparatus fordelivering a stream of air bearing entrained lawn debris; (B) aseparation chamber having an upper bulkhead and an outer wall; (C) afirst passage having an entrance and exit, having the entrance adaptedto receive the stream of air bearing entrained lawn debris, and beingadapted for conducting the stream of air bearing entrained lawn debrisfrom the entrance to the separation chamber and directing the stream ofair bearing entrained lawn debris into the separation chamber in adirection primarily tangential to the outer wall of the separationchamber; wherein the separation chamber is adapted to separate thestream of air bearing entrained lawn debris into an outerly locateddebris-enriched stream and an innerly located debris-depleted stream;(D) a generally centrally located second passage having an entrance andan exit, wherein the generally centrally located second passage isadapted for: (i) receiving the innerly located debris-depleted streamfrom the separation chamber through the entrance, and (ii) conductingthe innerly located debris-depleted stream to the exit and dischargingit into the atmosphere; (E) a baffle extending generally outwardly froma central point below the entrance to the second passage; having theouter periphery of the baffle spaced inwardly from the outer wall; and(F) an opening around the baffle into the interior of an accumulationchamber below the baffle, having the baffle disposed to permit passageof the innerly located debris-depleted stream into the second passagewhile impeding passage of fine particulates of reduced yard debris fromthe accumulation chamber into the air discharged from the separationchamber through the second passage; wherein the overall height of theapparatus from the uppermost portion of the apparatus to the plane ofthe outer periphery of the baffle is less than about 1.2 times theinside diameter of the separation chamber proximate the baffleperiphery.

Preferably, the connection of the exit of the first passage into theseparation chamber is disposed below the upper bulkhead.

In a preferred embodiment, the first passage is curvilinear in a planegenerally perpendicular to the axis of the outer wall and has itsconcave surface generally concentric about the axis.

Yet another aspect of this invention relates to a free-flow apparatusfor separating entrained lawn debris from a transporting air stream byaction of body forces thereupon, comprising: (A) an apparatus fordelivering a stream of air bearing entrained lawn debris having a flowrate of at least about 300 cubic feet per minute; (B) aprimary-separation duct having an entrance and exit, with the entranceadapted to receive the stream of air bearing entrained lawn debris, andthe duct adapted for conducting the stream of air bearing entrained lawndebris from the entrance to the exit; wherein the primary-separationduct (i) has a generally curvilinear outer surface spanning an arc of atleast about

-   -   arc cosine RI/RO        circumferentially along its length and has a radius of curvature        of its generally curvilinear outer surface less than about        36″, (ii) measures at least about 4″ perpendicular to its plane        of curvature and at least about 2″ in the radial direction,        and (iii) is adapted to direct the stream of air bearing        entrained lawn debris to flow generally circumferentially along        its length and initiate separation of the stream of air bearing        entrained lawn debris into an outerly located debris-enriched        stream and an innerly located debris-depleted stream, wherein    -   RI=radius of curvature of the generally curvilinear inner        surface of the primary-separation duct, and    -   RO=radius of curvature of the generally curvilinear outer        surface;        (C) a secondary-separation chamber less than about 36″ in        diameter and connected to the exit from the primary-separation        duct and having a generally annular outer wall defining a        primary axis generally co-incident with the center of curvature        of the generally annular outer wall, the secondary-separation        chamber further comprising a shape for (i) receiving and        directing the streams of air bearing entrained lawn debris from        the primary-separation duct in a direction generally tangential        to the generally annular outer wall of the secondary-separation        chamber, (ii) directing the outerly located debris-enhanced        stream from the primary-separation duct to flow along the outer        wall of the secondary-separation chamber; (iii) directing the        innerly located debris-depleted stream from the        primary-separation duct to flow radially inward of the        debris-enriched stream; and (iv) further separating the streams        of air bearing entrained lawn debris into an upwardly and        inwardly directed debris-depleted stream and a downwardly and        outwardly directed debris-enriched stream; (D) a generally        centrally located passage at least 4″ in diameter and having an        entrance and an exit, and having the perimeter of the entrance        located at least 2″ radially inward from the generally annular        outer wall of the secondary-separation chamber, wherein the        generally centrally located passage is adapted for: (i)        receiving the upwardly and inwardly directed debris-depleted        stream from the secondary-separation chamber through the        entrance, and (ii) conducting the upwardly and inwardly directed        debris-depleted stream to the exit and discharging it into the        atmosphere; (E) a baffle extending generally outwardly from a        central point below the entrance to the passage, having the        outer periphery of the baffle spaced at least 1″ inwardly from        the generally annular outer wall, and having the outer periphery        disposed less than 15″ below the entrance to the passage;        and (F) an opening around the baffle into the interior of an        accumulation chamber below the baffle; wherein the baffle is        disposed to permit passage of entrained yard debris in the        downwardly and outwardly directed debris-enriched stream into        the accumulation chamber while impeding passage of fine        particulates of reduced yard debris from the accumulation        chamber into air discharged from the separation chamber through        the passage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a typical apparatus made in accordancewith the present invention and showing certain principal features of theapparatus.

FIG. 2 is a side view of the apparatus of FIG. 1 with a portion of theapparatus shown in cross section view along the lines of 2—2 of FIG. 1.

FIG. 3 is a top view of a portion of the apparatus of FIG. 1 with thetransfer duct 92 removed at cross-section view along the lines of 3—3 inFIG. 2 to show elements of power supply to the chipper shredder and thecollector rotor.

FIG. 4 is a close-up view of the apparatus in FIG. 2 showing airflowaround the lower collector lip.

FIG. 5 is a front view of the chipper shredder shown as a cross sectionview along the lines of 5—5 of FIG. 2.

FIG. 6 is a cross section view of the chipper shredder taken along lines6—6 in FIG. 5 and showing the interaction of the swing hammers with theinwardly protruding teeth.

FIG. 7 is a perspective isolated view of the inwardly protruding teethshown at 82 in FIG. 5.

FIG. 8 is a perspective view of the primary separation loop shown inFIG. 1.

FIG. 9 is a cross sectional view of the separator and hopper as viewedalong lines 9—9 in FIG. 2.

FIG. 10 is a perspective isolated view of the collector rotor shown inFIG. 1.

FIG. 11 is a schematic perspective view of the collector duct shown inFIG. 2, including notation for design parameters.

FIG. 12 is a schematic view of raking tips that can be used with thecollector rotor shown in FIG. 10.

FIG. 13 is a cross-section view similar to a portion of FIG. 2, butshowing a forward location of a stripping slot which admits air to stripleaves from the rotor.

FIG. 14 is a cross-section view of a variation of the collector rotorshown in FIG. 13 in which flat fillets have been replaced with convexfillets.

FIG. 15 is a cross-section view of a variation of the collector rotorshown FIG. 14 showing an alternative design for fabricating thecollector rotor with convex fillet shapes.

FIG. 16 is a schematic top-view diagram of the primary-separation ductshowing mathematical notations for calculating minimal arc of curvaturefor effective separation of air and lawn debris.

FIG. 17 is a side view of a riding lawnmower having a collector assemblyand a separator of this invention.

FIG. 18 is a cross-section view of selected portions of the ridinglawnmower shown in FIG. 17.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1, deep collector 22 rests on surface 24 bearing deep yarddebris 26 comprising primarily leaves, twigs, clippings and othermaterials such as usually accumulate on lawns, sidewalks and patios inthe vicinity of trees in the autumn. Frame 28 of deep collector 22comprises right support plate 30, left support plate 32, base-plate 34and control handle structure 36. Upper housing 38 spans from rightsupport plate 30 to left support plate 32. Rotor shaft 40 journaledbetween left and right support plates 30 and 32 carries a plurality ofrotor blades 42, each of which is preferably substantially gasimpervious and bears a rotor tip which, in FIG. 1, may be asubstantially gas impervious flexible rotor blade tip such as thatindicated at 44. Rotor pulley 46 mounted on rotor shaft 40 engages drivebelt 48 which also engages idler pulley 50 mounted on lever arm 52pivotably mounted on right support plate 30. Drive pulley 54 isconnected to motive means 146 for powering deep collector 22. Bypivoting lever arm 52 clockwise, idler pulley 50 tightens drive belt 48,drawing it into firm engagement with rotor pulley 46 and drive pulley54, rotating rotor shaft 40 bearing rotor blades 42 and flexible rotorblade tips 44, which engage surface 24 upon rotation of rotor shaft 40.A shaft with rollers 47 can be raised and lowered on the support plates30 and 32 to conversely lower and raise the rotor blade tips 44 relativeto surface 24.

FIG. 3 shows details of power delivery to chipper shredder 66 and drivepulley 54. Conventional engine 146 disposed on base plate 34 has enginecrankshaft 148 extending into chipper shredder 66, chipper shredderrotor 74 being mounted on said engine crankshaft. Engine drive belt 150engages engine drive pulley 152 disposed on engine crankshaft 148 andsecond pulley 154 disposed on first power shaft 156. Reducing-angledrive 158 disposed at the intersection of first power shaft 156 andsecond power shaft 160 transmits power to drive pulley 54.

As shown in FIG. 2, as rotor blades 42 are driven counterclockwise,flexible rotor tips 44 proximately engage upper housing 38 impedingsubstantial passage of air between upper housing 38 and rotor blades 42.As the arc of upper housing 38 is at least a significant fraction of theincluded angle between adjacent rotor blades 42, a substantial seal topassage of air is provided above rotor shaft 40 throughout much or allof the rotation cycle of said rotor shaft. In preferred embodiments,rotor shaft 40 is at least about 2″ above surface 24, facilitatingengagement of rotor blade tips 44 with deep yard debris 26 having adepth considerably greater than 2″. In more preferred embodiments, upperlip 58 on upper housing 38 will be at least about 4″ inches abovesurface 24 permitting engagement with yard debris 26 having a depth ofthat order of magnitude. In more preferred embodiments, upper lip 58 ofupper housing 38 will be disposed at least about 8″ inches above surface24, more preferably at least about 12″. Yard debris 26 engaged betweenadjacent rotor blade tips 44 is thereby impelled rearwardly towardcollector duct 60 defined between upper collector shell 62 and lowercollector shell 64. Suction is supplied to collector duct 60 by chippershredder unit 66 which may be of any conventional construction such asthat shown in U.S. Pat. No. 5,931,396. For typical yard debris having adepth of several inches, we have obtained good results with unitsproviding at least about 20, preferably over 40, cubic feet per minute(cfm) of air flow per inch of width of the suction intake. While it isdesirable to have considerable shredding action to reduce the volume ofthe debris collected, even the minimal amount of shredding provided by asufficiently powerful fan can be adequate for effectively collectingleaves.

As generally indicated at 68 in FIG. 2, as flexible rotor blade tip 44moves toward lower collector lip 70 between right support plate 30 andleft support plate 32, flows of air having substantial components nearlyparallel to surface 24 are induced in close proximity to surface 24. Asshown in FIG. 4, as lower collector lip 70 is spaced from surface 24,forwardly and upwardly directed air flow generally indicated at 69around lower collector lip 70 provides enhanced vacuuming effect atsurface 24 during the period in which flexible rotor tips 44 are movingfrom the point of engagement with surface 24 toward lower collector lip70. Ideally, the lowermost portion of lower collector lip 70 is spacedfrom surface 24 by a height of about one tenth to about three quartersof the height of the opening to collector duct 60. Particularly enhancedsuction at surface 24 and air flow parallel to surface 24 occurs as eachflexible rotor blade 44 draws into closest proximity with surface 24.

In some preferred embodiments, suction in collector duct 60 comprises asteady level of suction having superimposed therewith pulsed suction,this combination of steady and pulsed suction providing excellentability to both induce flow of fine yard debris through collector duct60 while also impelling heavier yard debris through said collector ducttoward chipper shredder 66. Pulsing of the suction applied to collectorduct 60 is thought to result from the variable opening created betweenflexible rotor blade tips 44 and surface 24 as flexible rotor blades 44sweep rearwardly toward lower collector lip 70, attaining high velocityin collector duct 60 prior to rotor blade 42 and flexible rotor bladetip 44 coming into closest proximity with surface 24, and high suctionas rotor blade 42 and flexible rotor blade tip 44 come into closestproximity with lower collector lip 70.

Variable stripping slot 72 defined between upper housing 38 and uppercollector shell 62 admits a flow of air into voids between rotor blades42, aiding in removal of yard debris contained therebetween and reducingcycling of yard debris around rotor shaft 40. Ideally, the width ofvariable stripping slot 72 is sized to provide enough of an impulse toremove debris which might otherwise be carried around with the rotor,without unduly compromising the vacuum flow used for removal of finedebris from the ground. We have found that a width of from about onetenth to about three quarters of the height of the opening to collectorduct 60 is suitable for a 5 HP unit. We have also found that fillets 73installed between adjacent rotor blades 42 aid in reducing the amount ofdebris which might otherwise be carried around with the rotor.

Airflow induced by chipper shredder 66 entrains yard debris 26 andtransports said yard debris through collector duct 60 and into chippershredder 66. FIGS. 5, 6, and 7 show features of a preferred embodimentof chipper shredder 66. A shredder rotor 74 with swing hammers 76 andfan blades 78 rotates in chipper shredder enclosure 80. Swing hammers 76swing past inwardly protruding teeth 82, reducing the size of leaves andother entrained debris. An advantage of reducing the volume of thecollected leaves and other debris with the invention is to make itpossible to store a considerable mass of debris, reducing storage spacewhile reducing the tendency for wind to disperse the leaves. Branchesmay be introduced into chipper shredder enclosure 80 through chippershredder opening 84 and chipped by chipper knives 86. Reduced debrispasses through elongated gaps in swing hammer screen 88 and outwardthrough chipper shredder exhaust port 90.

Entrained debris from chipper shredder unit 66 is impelled throughtransfer duct 92 to separator 94 which separates entrained debris fromthe entraining air. As shown in FIG. 8, debris entrained in air passesfrom transfer duct 92 into separator 94 through separator inlet duct 96.Primary separation occurs in primary separation duct 98 as the flow ofair is redirected inwardly, while inertial forces urge debris solidstoward perimetral wall 100 of primary separation duct 98, therebyforming a solids-depleted inner layer and a solids-enriched outer layer.Primary separation duct 98 directs the flow of air-entrained yard debrisdownwardly as it enters secondary separation chamber 102 in FIG. 9,impelling downward flow of both solids-depleted inner air layergenerally indicated at 104 and solids-enriched outer layer generallyindicated at 106 through transfer opening 108 between primary separationduct 98 and secondary separation chamber 102.

As shown in FIG. 9, solids-depleted inner air layer generally indicatedat 104 flows downwardly in innermost portion of transfer opening 108,while solids-enriched outer layer generally indicated at 106 flowsdownwardly along first perimetral wall 100 into secondary separatorchamber 102. Rotating airflow indicated generally at 110 swirls aroundsecondary separation chamber 102, further separating debris into solidsenriched outer layer 106, which passes along second perimetral wall 112of secondary separation chamber 102 into hopper 114 below. To be mosteffective, this rotating airflow moves with a tangential velocity of atleast about 2000 feet per minute measured close to second perimetralwall 112, causing the entrained reduced lawn debris to move outwardlytoward second perimetral wall 112 of secondary-separation chamber 102 byaction of body forces thereupon. Second perimetral wall 112 may consistof some combination of cylindrical and frusto-conical surfaces, and isreferred to as a frusto-conical outer wall section. Swirling continuesin hopper 114, while infundibulate baffle 116 impedes secondary flows ofair containing finely reduced debris fragments from re-enteringsecondary separation chamber 102. In secondary separation chamber 102,solids-depleted inner air layer generally indicated at 105 migratesupwardly along the axis of secondary separation chamber 118, throughexhaust entrance 120, which passes through upper bulkhead 121, and exitsthrough exhaust passage 122 to the atmosphere. Infundibulate baffle 116is suspended below secondary separation chamber 102 by supporting rods117 or by other supporting means. If desired, deflector 125 can beplaced adjacent to exit 123 of exhaust passage 122 to direct airflowgenerally indicated at 127 away from person operating apparatus.

As most of the separation is achieved by the action of body forces onthe particles of entrained debris, the flow through the separator issubstantially unimpeded—in contrast to those units in which filtrationis primarily relied upon to remove the particulate debris from theair-stream in which it is entrained. Hence, this separator is referredto as a free-flow apparatus. Even though a minimal filter may be placedin the exhaust stream from the separator if so desired, the flow throughthe separator is substantially free of obstructions which might limitthe flow of air significantly if filtration were relied upon for primaryremoval of heavy debris. Thus, the invention provides a machine whicheffectively separates the reduced yard debris from the air in which itis entrained, and which can be operated effectively for an extendedperiod without either stopping to clear a filter in the separator, orexperiencing decreased pick-up efficacy because of reduced air flow rateoccasioned by partial blockage of a filter area.

Since the apparatus of the invention separates the debris from the airstream without relying primarily on a filter element, another aspect ofthe invention is to be able to collect the reduced debris in animpervious receptacle. Thus, the receptacle may be a barrel-likecontainer, a fabric bag of limited permeability, a plastic bag, or apaper bag. One may also deploy a flexible container, such as a plasticor paper bag, within a rigid barrel-like container.

Another aspect of the invention is that it provides a machine having aseparator and collector container low enough in height that the operatorwill be able to see over the separator in order to operate the machineeffectively, while the collector container still has substantialcapacity for accumulating debris. Accordingly, it is preferable that theoverall height of the apparatus from the uppermost portion of theapparatus to the outer baffle periphery be less than about 1.2 times theinside diameter of the separation chamber as measured proximate thebaffle periphery. It is further preferable that the plane of the baffleperiphery be disposed below the lowermost portion of the upper bulkheadby a distance of less than about 0.6 times the inside diameter of theseparation chamber. In some configurations, it is preferable that thebaffle periphery be disposed below the lowermost portion of the entranceto the exhaust passage by a distance of less than about 0.6 times theinside diameter of the separation chamber.

Further in FIG. 9, upon being filled with retained debris 124, hopper114 may be opened by sliding apart upper and lower flanges 126, allowingretained debris 124 accumulated therein to be discarded. Thus, anotherfeature of the invention is in providing a debris-collection receptaclewhich can be emptied quickly and easily.

FIG. 10 further displays construction of collector rotor 128 comprisingrotor shaft 40, rotor blades 42, flexible rotor blade tips 44, adjustingnuts 130 for adjusting flexible rotor blade tips 44 for properengagement with surface 24, and left seal disc 132 and right seal disc134 for assisting in rigidifying of rotor blades 42 while substantiallyimpeding axial air flow into spaces between rotor blades 42.

FIG. 11 shows a preferred configuration for collector duct 60, having acollector duct entrance 136, a collector duct exit 138, and aconvergence angle Φ preferably less than about 120°. In preferredembodiments, convergence angle Φ will be less than 110°. In morepreferred embodiments, convergence angle Φ will be less than 100°, mostpreferably less than 80°. In other preferred embodiments, the crosssectional area of collector duct 60 measured in planes (generallyindicated at 140) perpendicular to central flow line (generallyindicated at 142) will be approximately constant along length ofcollector duct 60. In more preferred embodiments, cross sectional areaat any point along collector duct 60 will be within about 15 percent ofthe average of the minimum and maximum values.

FIG. 12 displays optional raking tips 144 which may be attached to rotorblade 42, enabling use of deep collector 22 for raking debris from agrass-covered surface such as a lawn or other crinose surface such asAstroturf®.

FIG. 13 illustrates stripping slot 72 in a closed position and forwardstripping slot 151 in upper housing 38 being located in a preferredforward position. The advantage of forward placement of stripping slot151 is that air bleed into collection duct 60 occurs for only a fractionof the rotor revolution, instead of being almost continuous as with openrear stripping slot 72. Rear upper housing segment 153 spans theequivalent of about two thirds of the arc distance between adjacentrotor tips 157. Rotor blade tips 157 move in individual proximity withrear upper housing segment 153 for about two thirds of the revolutioncycle, and air bleeds through forward stripping slot 151 for only aboutone third of the cycle. It appears that more of the air admitted tocollection duct 60 comes from flows 163 along surface 24 and less fromstripping slot 151, resulting in believed greater efficiency incollecting debris from surface 24. It also appears that air flow throughforward stripping slot 151, through rotor cavity 159, and intocollection duct 60 has more action in stripping leaves from rotor cavity159 than would air flowing through rear stripping slot 72 and intocavity 159. However, even with airflow through forward stripping slot151, rotational secondary flows were detected as generally indicated at161. These secondary flows appeared to enable leaves to stay in rotorpockets 159 and carry over to open front 162 of the housing, where theywere re-deposited on surface 24.

FIG. 14 illustrates convex fillets 164 being used instead of flatfillets 73 shown in FIG. 2. Convex fillets 164 define thinner rotorcavities 166 that are generally concentric with rotor shaft 40 and whichexhibit greatly reduced or no detectable macro-scale eddy flows uponairflow through forward stripping slot 151. One could use fillets havinggenerally concentric, generally convex surfaces having a number of smallflat, dimpled, or other shaped surfaces, and still achieve a generallyconvex cavity space. The shape and dimensions of said convex filletsshould be chosen such that any substantial, detectable local flowsgenerally indicated at 168 move rearward from forward stripping slot 151to collection duct 60. Forward carryover and re-deposition of leaveswere greatly reduced with use of convex fillets 164.

An alternative construction of rotor 170 is illustrated in FIG. 15. Oneskilled in the art will recognize that as an alternative to constructingrotor 128 with blades 42 as in FIG. 10, and convex fillets 164 as inFIG. 14, one could employ a tubular member 172 concentric with rotorshaft 40 and having means 174 for attaching rotor blade tips 44 (FIG.10) or raking tips 144 (FIG. 12).

FIG. 16 is a schematic top-view diagram of separator 94 shown in FIGS. 8and 9. Primary-separation duct 98 has a radius RO of its curvilinearouter surface 100, a radius RI of its curvilinear inner surface 101, anda minimum arc of curvature Θ for effective separation of debris-ladenair generally indicated at 99 into a solids-enriched outer layergenerally indicated at 106 and a solids-depleted inner layer generallyindicated at 104. Both layers pass through transfer opening 108 intosecondary separator chamber 102 in FIG. 9, and then solids-depletedinner air layer passes upward through exhaust passage 120 in FIG. 16.Minimum arc of curvature for effective separation Θ is related to theradii of curvature by the expressions:cosine Θ=RI/RO; andΘ=arc cosine RI/RO.

FIG. 17 illustrates riding lawnmower 176 having collector assembly 178mounted at advancing entrance 180 of mower deck 182. Leaf fragments andgrass clippings are separated from entraining air by separator 94 andretained in hopper 114.

FIG. 18 depicts a cross section view of selected portions of ridinglawnmower 176 shown in FIG. 17. Leaves and other debris are impelled bycollector rotor 170 into mowing chamber 186 within the mowing enclosure188, where they are reduced by mower blades 190. Fan 192 induces airflowunder collector rotor 170, through mowing chamber 186, first air duct194, and second air duct 196, and into separator 94, entraining leaffragments, grass clippings, and other debris into hopper 114.

EXAMPLE 1

A commercially marketed machine made according to the design shown inU.S. Pat. No. 5,642,864 was used to collect leaves on a lawn and shredthem. The machine had an intake opening about 25 inches long and 4inches wide with the damper at its maximum open position. The openingwas inclined forward at about 45 degrees to the ground, giving aneffective opening height of about 2.8″. The chamber behind the damperwas a solid rectangle in shape and about six inches front to back. Astraight rectangular duct led from an opening in one end of the chamberto the center of a chipper-shredder-blower having its axis of rotationperpendicular to the direction of forward movement. The blowerdischarged into a large bag made of thick cloth and having amesh-covered opening for venting entraining air. A zipper opening wasprovided for emptying collected debris.

A covering of fresh, dry leaves about three to six inches deep waspresent on the lawn. In addition, piles of leaves about six to twelveinches thick were also present. The machine was advanced into a pile ofleaves, but the front opening pushed the leaves ahead of it instead ofdrawing the leaves into the opening. The machine was adjusted to raisethe front opening to its maximum height, but it still pushed leavesahead of it. Collection of leaves from the thinnest coverings on thelawn was attempted, but the machine still had a strong tendency to pushleaves ahead of it. The damper was disconnected and opened as wide aspossible, but still with little improvement in leaf collection.

In the belief that the machine performance was limited by low air flowcaused by leaf build-up on the mesh opening and resultant flowrestriction, the zipper opening was partially opened in the hope ofallowing more air flow. Leaf pick-up by the vacuum slot improvedsomewhat, but was still unsatisfactory. In addition, a stream of leaffragments blew through the zipper opening, as expected.

The conclusion was that the machine might work marginally well with avery thin layer one or two leaves thick, up to perhaps about an inch indepth, but this approach would require using the machine multiple timesthroughout normal leaf fall.

EXAMPLE 2

Following the experience of example 1, collecting leaves with aconventional 26-inch, two-stage snow blower was attempted to see if theauger-feed mechanism would function with leaves. Indeed, the augerreadily fed even the deepest piles of leaves into the second-stageblower, which blew them 10–15 feet away. However, this approach left athin layer of leaves and other debris on the lawn where the pick-upauger had passed.

The conclusion was that a machine with a similar auger-feed pick-upwould collect even deep piles of leaves. However, the user would need togo over the lawn a second time with a different machine to collect thethin layer of residual leaves and other debris.

EXAMPLE 3

A machine of the current invention was built according to the drawingsin FIGS. 1–11. A Yard Man 5-horsepower chipper-shredder-vacuum machinebuilt by MTD Products was purchased; the chipper-shredder unit andattached drive motor were removed from the purchased machine; and thenthey were mounted on the base plate of the current machine. The machinewidth between the left support plate and the right support plate was24.″ The collector rotor diameter was 15″, and it turned 65 revolutionsper minute. The front, upper edge of the housing over the rotor wasabout 13½″ above the support surface. The lowermost portion of the lowercollector lip was about 1″ above the supporting surface when measuredwith the machine sitting on a concrete slab. The collector duct had anentrance opening 2½″ high and 24″ wide with a cross sectional area of 60square inches, an exit opening about 6″ high and 9″ wide with a crosssectional area of about 54 square inches, and a convergence angle of76°. The stripping slot was closed. The 5-horsepower engine turned 3450revolutions per minute. The channel of the primary separation loopmeasured 4″ wide and 8″ high and ended with a constricted opening 1¾wide and 8″ high upstream of the downward sloping entrance to thesecondary separation chamber. The effective curvature of the loop wasabout 305°, and the outside radius of curvature was about 10⅝″. Theinside diameter of the secondary separation chamber was about 23″. Theradial clearance between the perimeter of the baffle and the wall of thesecondary chamber was about 1⅜″, and the baffle perimeter was about 7″below the transfer opening. The exhaust port was 7″ in diameter, and theairflow through the machine was about 540 cubic feet per minute (cfm)(22.5 cfm per inch of machine width). The effective hopper volume (belowthe baffle) was about 40 gallons.

Leaves were spread on a lawn in thicknesses varying from about 2″ toabout 10″. The machine was set into operation and advanced through theleaves. Leaf overlayers of all thicknesses were readily collected, andno pushing of leaf piles ahead of the machine occurred. The volume ofthe leaves was reduced, and the leaf fragments were retained in thehopper. The entraining air exited through the separator exhaust passage,carrying with it only fine dust. Some leaves and debris were left in thewake of the machine, meaning that the machine was proving to beexceptionally effective in removing deep piles of leaves but left somefiner debris behind. It appeared that the airflow was not quite greatenough to get optimum cleaning. Also, it was observed that when themachine was pulled backward, the cleaning was more thorough, suggestingthat the collector rotor should be turning faster.

Another observation was that some leaves were remaining with thecollector rotor and carrying over the top of the rotor, being impelledonto the grass in front of the machine, or blown by side winds onto partof the lawn which had already been cleaned.

EXAMPLE 4

The machine of Example 3 was modified as follows: In order to increasethe air flow rate, (1) the engine speed was increased from 3450 to 3680revolutions per minute; (2) the constriction in the primary separationloop was removed, leaving the channel size throughout the loop at 4″wide and 8″ high; (3) the transfer opening was enlarged to about 100square inches; and (4) the separator exhaust port was enlarged from 7″to 9⅛″ diameter. The airflow rate was then measured at 1000 cubic feetper minute (41.7 cfm per inch of machine width). The collector rotorspeed was increased from 65 to 276 revolutions per minute. In order toreduce the number of leaves carried over the top of the turningcollector rotor, the stripping slot was opened to 1″. The diameter ofthe baffle in the separator was reduced, leaving an annular radialclearance of about 2⅜″ between the baffle perimeter and the outside wallof the secondary chamber. The perimeter of the baffle was 5¼″ below theceiling of the secondary separation chamber.

The machine was operated in leaf overlayers of 3″ to 12″ and readilyremoved the leaves. No leaves and little other debris were left in thepath of the machine, and carryover of leaves over the top of thecollector rotor was reduced. The separator retained the leaf fragmentsand exhausted air containing only a small amount of very fine dust, andwas judged to operate quite satisfactorily. It was considered remarkablethat in the deep piles of leaves the machine could be moved forward intothe leaves at a pace and with a concomitant leaf-feed rate that began tooverload the shredder, but the collector rotor, collector duct, andseparator continued to function well.

EXAMPLE 5

In order to achieve more aggressive raking action to lift leaves andother debris from the lawn surface, the continuous but flexiblerubberized rotor blade tips 44 were replaced with rake-like teeth shownin FIG. 12. To make these teeth, pieces of polycarbonate sheet plasticapproximately 6″ wide by 23⅜″ long and 1/16″ thick were sawn withparallel cuts spaced every ½,″ sawing from the long edge of the sheet 3″to the center of the sheet. The saw kerfs were about 1/32″ wide; so thatminimal airflow between adjacent teeth would occur. The tips of the“teeth” were bent about 30°. This bending was done with thepolycarbonate sheet at room temperature. A strip of raker teeth wasbolted to each of the rotor blades such that the teeth extended radially5/16″ beyond the edges of the seal discs on the ends of the rotor. Byadjusting the height of the front-support rollers, the tips of the rakerteeth were set about 1/16″ above a flat concrete surface.

The machine was then operated on a lawn. The raker teeth readily removedleaves, hickory nuts, shells, dead grass, and even some live grass,especially if the machine was allowed to run in one place very longwithout moving. The conclusion is that one could adjust the machine torake as aggressively as desired.

Another observation was that carryover of leaves, nuts, etc. over thetop of the rotor was increased, perhaps due to the positive rake angleof the teeth.

EXAMPLE 6

After seeing leaves carried over the top of the collector rotor anddischarged frontward in Example 5, an attempt was made to eliminate thiscarryover. The existing stripping slot was closed, and a new forwardslot was cut in the arcuate housing as shown in FIG. 13. The slot wasabout 1 1/16″ wide and began about 9⅝″ forward of the closed strippingslot, as measured along the arc of the housing cover. Since theremaining continuous housing spanned approximately two thirds of the arcbetween two adjacent sets of raker teeth, a substantially imperviousblade would be in close proximity to the housing two thirds of the timeof each revolution of the rotor (Two ninths of the time for eachindividual blade; two thirds of the time cumulative for the three bladesthrough one rotation). Thus, the blades moving under the housing wouldprevent significant reverse flow of air from occurring for roughly ⅔ ofthe time during a rotor revolution. Conversely, reverse flow (from thenew slot to the collecting duct) was permitted for about ⅓ of a rotorrevolution. Furthermore, the slot was placed such that when one rotortip (or row of raker teeth) had just passed the new stripper slot andallowed reverse air flow through the slot and into the collector duct,the following rotor tip would be in general proximity to the lowercollector lip 70. Thus, flow through the stripping slot occurred duringa phase of the rotor revolution when diminished airflow would have beenpassing into the collector duct from the supporting surface anyway. Theintent of this design was to minimize lost vacuuming effectiveness bytrying to maintain as much airflow as possible along the lawn surfaceand into the collector duct.

Unfortunately, this change achieved little reduction in the amount ofleaf carryover.

EXAMPLE 7

With the machine fan operating, and with the collection rotor stopped inthe position shown in FIG. 13, a thread on the end of a wire was used asa “tell tale” to detect the directions of air movement in the spacebetween the two blades forming a flow space adjacent to the newstripping slot and the collector duct. The airflow directions aresketched approximately in FIG. 13, showing there was a very strongreverse eddy. The presence of this eddy may help explain how there couldstill be strong carryover of the leaves, as this secondary air flowprobably prevented stripping the leaves out of the cavity between theadjacent blades, even with the flat fillets in place.

To overcome the leaf carryover in the eddies, convex fillets weresubstituted for the flat ones, as shown in FIG. 14. The outer surfacesof the fillets were about 1½″ radially inward of the tips of the rakerteeth and about 1¼″ radially inward of the perimeters of the rotor sealdiscs. Testing with the “tell tale” showed that the eddy flow had beeneliminated, and that all of the detectable localized airflows in thereduced cavity were in the rearward direction—from the new strippingslot and toward the collection-duct entrance. Operation of the machineon a lawn showed that leaf carryover had in fact been greatly reduced.However, there was still some carryover of nuts and shells.

EXAMPLE 8

In an attempt to stop the carryover of nuts and shells, raker bladeswere made having teeth bent with a negative rake angle. The intent wasto make sure the positive rake angles of the first raker teeth were notresponsible for retaining the nuts on the rotor and enhancing carryover.However, upon operation of the machine on the lawn, carryover of nutsand shells with forward discharge continued. Notably, leaf pickup wasnot as effective as with the positive rake angle.

In the possibility that the carryover was simply a momentum effect, thecollector rotor speed was reduced in half—from 276 to 138 rpm (with arotor peripheral velocity of 542 feet per minute, or 6.16 miles perhour). The carryover of nuts, shells, and other dense debris almostcompletely stopped. The raker blades with positive rake angle werere-installed, and the carryover was still absent, while virtuallycomplete removal of leaves and other debris from the lawn was achieved.

EXAMPLE 9

The bag-holder assembly of a Simplicity riding lawnmower model 12FCH42was removed, and the hopper and separator were removed from the machinedescribed in Examples 3 and 4. The hopper and separator were set on theback base plate of the Simplicity machine and were connected to the airduct which had been connected to the lawnmower bag-holder assembly. TheSimplicity machine had a blower mounted on the right end of the 42-inchmower deck, and the duct transported air, clippings, and leaf debrisfrom the blower to the entrance of the separator inlet duct. The blowerdelivered 770 cfm of entraining air, and the separator exhaust port was9⅛″ in diameter.

The lawnmower was operated on a lawn having a thin covering of leaves,and the grass had grown about 1½ inch since its previous cutting. Themower blades cut the grass and did some chopping of the leaves, and theblower directed the debris to the separator. The separator performedwell, retaining the debris in the hopper and exhausting the airvirtually free of debris fragments.

EXAMPLE 10

To evaluate the possibility that the machine could also function as asnow blower, the elbow in the transfer duct 92 was disconnected from theseparator 94 and directed to one side of the machine. Without making anyfurther changes, the machine was started and advanced into fresh snowabout 3 to 4″ deep. The combination rotor and vacuuming actionsuccessfully lifted the snow, which passed through the collector duct,into the shredder-blower, and out the discharge (transfer) duct.

1. An apparatus for collecting and reducing yard debris comprising: a. aframe adapted for movement in a principal direction upon a surface; b. afirst duct mounted on said frame having an entrance and an exit; c. acollector rotor assembly comprising: a collector rotor body disposed atthe entrance to said first duct having a substantially horizontal axisof rotation generally normal to said first direction; and a plurality ofimpeller elements mounted upon said collector rotor body, said impellerelements being adapted to: i. engage and sweep over said surface, ii.collect yard debris thereupon, and iii. impel said yard debris towardsaid duct entrance,  said impeller elements extending radially from saidcollector rotor body by at least about one quarter of an inch;  saidcollector rotor assembly and said first duct being configured forsubstantially untrammeled frontal engagement with yard debris having adepth of at least about two (2) inches; d. a second duct having anentrance and an exit; e. a blower unit, disposed between said exit tosaid first duct and said entrance to said second duct, adapted to: i.provide suction at said entrance of said first duct, ii. induce a flowof air through said first and second ducts, and iii. reduce yard debrisentrained in said flow of air as it passes through said blower unit; f.an air-solids separator disposed at said exit to said second duct forseparating said reduced yard debris in said flow of air induced by saidblower into a debris-enriched stream and a debris-depleted stream; g.means for discharging said debris-depleted stream to the atmosphere; h.an accumulation operatively connected to said air-solids separator andadapted to receive said debris-enriched stream from said air-solidsseparator; i. means operatively connected to said blower unit andadapted to provide power to said blower unit; and j. means operativelyconnected to said collector rotor assembly and adapted to provide powerto said collector rotor assembly.
 2. The apparatus of claim 1 whereinsaid impeller elements extend radially at least about an inch from saidcollector rotor body.
 3. The apparatus of claim 1 wherein said collectorrotor assembly comprises a substantially gas-impervious impediment tounrestricted flow of air into said first duct and extends substantiallyathwart said entrance to said first duct.
 4. The apparatus of claim 1wherein said collector rotor assembly comprises three impeller elementsgenerally equispaced around said collector rotor body.
 5. The apparatusof claim 3 wherein said collector rotor assembly further comprisesfillets extending between adjacent impeller elements for limitingcarriage of yard debris around said collector rotor assembly, whereinsaid fillets partially define generally concentric interrupted annularcavity spaces between adjacent impeller elements.
 6. The apparatus ofclaim 1 further comprising a housing adapted to limit the flow of airbetween said housing and said collector rotor assembly withoutsubstantially impeding air flow along said surface under said collectorrotor assembly and into said entrance of said first duct, said housing:a. being disposed above said collector rotor assembly, b. engaging eachof said impeller element tips in flow-limiting proximity seriatim, andc. being configured to permit substantially untrammeled frontalengagement of said collector rotor assembly with said yard debris havinga depth of at least about two (2) inches.
 7. The apparatus of claim 1further comprising vertically extending seals carried on said frameadjacent to the ends of said collector rotor assembly for limiting axialflow of air flow into said collector rotor assembly.
 8. The apparatus ofclaim 1 further comprising vertically extending seals carried on theends of said collector rotor assembly for limiting axial flow of airinto said collector rotor assembly.
 9. The apparatus of claim 6 whereinsaid housing defines a frontal opening extending from said surfacevertically to a height of at least four inches and a suction openingunder said rotor extending rearwardly from the front of said apparatusat least to a line below said axis of rotation of said collector rotorbody.
 10. The apparatus of claim 6 wherein said impeller elementsmounted on said collector rotor body are configured to allowintermittent rearward rushes of air under the forward side of saidrotating rotor body into said entrance to said first duct, and pulsedforward rushes of air under said first duct and into said first ductentrance, thereby alternatingly collecting principally bulky yard debrisfrom said forward side of said rotor body during said rearward rushes ofair and enhancing collection of residual debris from said surface duringsaid pulsed forward rushes of air.
 11. The apparatus of claim 6 furthercomprising an air-slot defined within said housing between the upper lipof said housing and said entrance to said first duct for allowing flowof air in a direction opposed to the direction of rotation of saidcollector rotor body and into said first duct and stripping leaves anddebris from said rotating rotor assembly.
 12. The apparatus of claim 1wherein said entrance to said first duct generally spans the length ofsaid collector rotor body and said first duct converges rearwardly suchthat the convergence angle throughout the duct is generally less than100 degrees.
 13. The apparatus of claim 1 wherein said air-solidsseparator comprises: a. a first passage for accepting said flow of airbearing entrained reduced yard debris from said second duct; b. aseparation chamber adapted to receive said flow of air from said firstpassage; c. a second passage adapted to exhaust said debris-depletedstream from said separation chamber into the atmosphere; and d. a bafflefor: i. generally inhibiting secondary flow from said accumulator; andii. impeding re-entrainment of fine particulates in said debris-depletedstream as it is discharged to the atmosphere;  said baffle beingdisposed between said separation chamber and said accumulator; and  saidbaffle being disposed to permit passage of entrained reduced yard debrisinto said accumulation means while impeding passage of fine particulatesof reduced yard debris in air exhausted from said separation chamberthrough said second passage.
 14. The apparatus of claim 1 wherein thetips of said impeller elements further comprise pliable blades adaptedfor engaging an undulating surface, said pliable blades being yieldableto hard objects encountered on said surface, but being sufficientlystiff to sweep debris from undulations present in said surface.
 15. Theapparatus of claim 1 wherein the tips of said impeller elements compriserows of radially-extending raker teeth adapted to engage and impeldebris objects on said surface toward said entrance of said first duct.16. The apparatus of claim 1 wherein the cross-sectional area of thechannel through said first duct measured normal to the center flow lineof said airflow through said first duct remains generally constant alongsaid center flow line.
 17. The apparatus of claim 1 further comprising alawnmower mounted on said frame wherein said collector rotor assembly isdisposed along the advancing front of said lawnmower, and said entranceof said first duct is operatively connected to said lawnmower to receivesaid yard debris.
 18. The apparatus of claim 17 wherein said collectorrotor assembly impels said yard debris into the mowing chamber withinthe mowing enclosure of said lawnmower, and said entrance of said firstduct receives said yard debris from a discharge opening of said mowingenclosure.
 19. The apparatus of claim 1 further comprising at least oneadjustable-height roller adjacent said collector rotor assembly adaptedfor supporting said collector rotor assembly at adjustable heights abovesaid surface whereby the degree of engagement of said impeller elementswith said surface may be controlled.
 20. The apparatus of claim 1wherein said collector rotor assembly is adapted to rotate with animpeller tip velocity of at least about three miles per hour.
 21. Theapparatus of claim 1 wherein said first duct converges between said ductentrance and said duct exit.
 22. The apparatus of claim 1 wherein saidentrance of said first duct generally spans the length of said collectorrotor body.
 23. The apparatus of claim 1 wherein said entrance of saidfirst duct generally spans the collective width of said impellerelements.
 24. The apparatus of claim 1 wherein said first duct has aconvergence angle of less than about 120°.
 25. The apparatus of claim 1wherein said air-solids separator comprises a free- flow apparatus forseparating said lawn debris from said flow of air by action of bodyforces thereupon.
 26. An apparatus for collecting and reducing yarddebris comprising: a. a frame adapted for movement in a principaldirection upon a surface; b. a first duct mounted on said frame havingan entrance and an exit; c. a collector rotor assembly comprising: acollector rotor body disposed at the entrance to said first duct havinga substantially horizontal axis of rotation generally normal to saidfirst direction; and a plurality of impeller elements mounted upon saidcollector rotor body, said impeller elements being adapted to: i. sweepover said surface, ii. collect yard debris thereupon, and iii. impelsaid yard debris toward said duct entrance,  said impeller elementsextending radially from said collector rotor body by at least about onequarter of an inch;  said collector rotor assembly further comprisingfillets extending between adjacent impeller elements for limitingcarriage of yard debris around said collector rotor assembly;  saidcollector rotor assembly and said first duct being configured forsubstantially untrammeled frontal engagement with yard debris having adepth of at least about two (2) inches; d. a second duct having anentrance and an exit; e. a blower unit, disposed between said exit tosaid first duct and said entrance to said second duct, adapted to: i.provide suction at said entrance of said first duct, ii. induce a flowof air through said first and second ducts, and iii. reduce said yarddebris entrained in said flow of air as it passes through said blowerunit; f. an air-solids separator disposed at said exit to said secondduct for separating said reduced yard debris in said flow of air inducedby said blower into a debris-enriched stream and a debris-depletedstream; g. an accumulator operatively connected to said air-solidsseparator and adapted to receive said debris-enriched stream from saidair-solids separator; h. means operatively connected to said blower unitand adapted to provide power to said shredder unit; and i. meansoperatively connected to said collector rotor assembly and adapted toprovide power to said collector rotor.
 27. The apparatus of claim 26wherein said fillets mean partially define generally concentricinterrupted annular cavity spaces between adjacent impeller elements,and wherein the radii of said fillets are at least about one third ofthe swing radii of the tips of said impeller elements mounted upon saidcollector rotor body.
 28. An apparatus for collecting and reducing yarddebris comprising: a. a frame adapted for movement in a principaldirection upon a surface; b. a first duct mounted on said frame havingan entrance and an exit; c. a collector rotor assembly comprising: acollector rotor body disposed at the entrance to said first duct havinga substantially horizontal axis of rotation generally normal to saidfirst direction; and a plurality of impeller elements mounted upon saidcollector rotor body, said impeller elements being adapted to: i. sweepover said surface, ii. collect yard debris thereupon, and iii. impelsaid yard debris toward said duct entrance,  said impeller elementsextending radially from said collector rotor body by at least about onequarter of an inch;  said collector rotor assembly and said first ductbeing configured for substantially untrammeled frontal engagement withyard debris having a depth of at least about two (2) inches; d. alawnmower mounted on said frame wherein the collector rotor assembly isdisposed along the advancing front of said lawnmower and the entrance ofthe first duct is operatively connected to said lawnmower to receivesaid yard debris; e. a second duct having an entrance and an exit; f. ablower unit, disposed between said exit to said first duct and saidentrance to said second duct, adapted to: i. provide suction at saidentrance of said first duct, ii. induce a flow of air through said firstand second ducts, and iii. reduce yard debris entrained in said flow ofair as it passes through said blower unit; g. an air-solids separatordisposed at said exit to said second duct for separating said reducedyard debris in said flow of air induced by said blower into adebris-enriched stream and a debris-depleted stream; h. an accumulatoroperatively connected to said air-solids separator and adapted toreceive said debris-enriched stream from said air-solids separator; i.means operatively connected to said blower unit and adapted to providepower to said blower unit; and k. means operatively connected to saidcollector rotor assembly and adapted to provide power to said collectorrotor.
 29. The apparatus of claim 28 wherein said collector rotorassembly impels said yard debris into the mowing chamber within themowing enclosure of said lawnmower and said entrance of said first ductreceives said yard debris from a discharge opening of said mowingenclosure.
 30. An apparatus for collecting and reducing yard debriscomprising: a. a frame adapted for movement in a principal directionupon a surface; b. a first duct mounted on said frame having an entranceand an exit; c. a collector rotor assembly comprising: a collector rotorbody disposed at the entrance to said first duct having a substantiallyhorizontal axis of rotation generally normal to said first direction;and a plurality of impeller elements mounted upon said collector rotorbody, said impeller elements being adapted to: i. sweep over saidsurface, ii. collect yard debris thereupon, and iii. impel said yarddebris toward said duct entrance,  said impeller elements extendingradially from said collector rotor body by at least about one quarter ofan inch;  wherein said collector rotor assembly comprises asubstantially gas-impervious impediment extending substantially athwartsaid entrance to said first duct to direct flow of air along saidsurface into said first duct; and  said collector rotor assembly andsaid first duct being configured for substantially untrammeled frontalengagement with yard debris having a depth of at least about two (2)inches; d. a second duct having an entrance and an exit; e. a blowerunit, disposed between said exit to said first duct and said entrance tosaid second duct, adapted to: i. provide suction at said entrance ofsaid first duct, ii. induce a flow of air through said first and secondducts, and iii. reduce yard debris entrained in said flow of air as itpasses through said blower unit; f. an air-solids separator disposed atsaid exit to said second duct for separating said reduced yard debris insaid flow of air induced by said blower into a debris-enriched streamand a debris-depleted stream; g. an accumulator operatively connected tosaid air-solids separator and adapted to receive said debris-enrichedstream from said air-solids separator; h. means operatively connected tosaid blower unit and adapted to provide power to said blower unit; andi. means operatively connected to said collector rotor assembly andadapted to provide power to said collector rotor.
 31. The apparatus inclaim 30 further comprising a housing adapted to limit the flow of airbetween said housing and said collector rotor assembly withoutsubstantially impeding air flow along said surface under said collectorrotor assembly and into said entrance of said first duct, said housing:a. being disposed above said collector rotor assembly, b. engaging eachof said impeller element tips in flow-limiting proximity seriatim, andc. being configured to permit substantially untrammeled frontalengagement of said collector rotor assembly with said yard debris havinga depth of at least about two (2) inches.
 32. An apparatus forcollecting and reducing yard debris comprising: a. a frame adapted formovement in a principal direction upon a surface; b. a first ductmounted on said frame having an entrance and an exit; c. a collectorrotor assembly comprising: a collector rotor body disposed at theentrance to said first duct having a substantially horizontal axis ofrotation generally normal to said first direction; and a plurality ofimpeller elements mounted upon said collector rotor body, said impellerelements being adapted to: i. sweep over said surface, ii. collect yarddebris thereupon, and iii. impel said yard debris toward said ductentrance,  said impeller elements extending radially from said collectorrotor body by at least about one quarter of an inch;  said collectorrotor assembly and said first duct being configured for substantiallyuntrammeled frontal engagement with yard debris having a depth of atleast about two (2) inches; d. a second duct having an entrance and anexit; e. a blower unit, disposed between said exit to said first ductand said entrance to said second duct, adapted to: i. provide suction atsaid entrance of said first duct, ii. induce a flow of air through saidfirst and second ducts, and iii. reduce yard debris entrained in saidflow of air as it passes through said blower unit; f. an air-solidsseparator disposed at said exit to said second duct for separating saidreduced yard debris in said flow of air induced by said blower into adebris-enriched stream and a debris-depleted stream; g. an accumulatoroperatively connected to said air-solids separator and adapted toreceive said debris-enriched stream from said air-solids separator; h.means operatively connected to said blower unit and adapted to providepower to said blower unit; and i. means operatively connected to saidcollector rotor assembly and adapted to provide power to said collectorrotor; wherein said collector rotor assembly is adapted to rotate withan impeller tip velocity of at least about three miles per hour.
 33. Anapparatus for collecting and reducing yard debris comprising: a. a frameadapted for movement in a principal direction upon a surface; b. a firstduct mounted on said frame having an entrance and an exit; c. acollector rotor assembly comprising: a collector rotor body disposed atthe entrance to said first duct having a substantially horizontal axisof rotation generally normal to said first direction; and a plurality ofimpeller elements mounted upon said collector rotor body, said impellerelements being adapted to: i. sweep over said surface, ii. collect yarddebris thereupon, and iii. impel said yard debris toward said ductentrance,  said impeller elements extending radially from said collectorrotor body by at least about one quarter of an inch;  said collectorrotor assembly and said first duct being configured for substantiallyuntrammeled frontal engagement with yard debris having a depth of atleast about two (2) inches; d. a second duct having an entrance and anexit; e. a blower unit, disposed between said exit to said first ductand said entrance to said second duct, adapted to: i. provide suction atsaid entrance of said first duct, ii. induce a flow of air through saidfirst and second ducts, and iii. reduce yard debris entrained in saidflow of air as it passes through said blower unit; f. an air-solidsseparator disposed at said exit to said second duct for separating saidreduced yard debris in said flow of air induced by said blower into adebris-enriched stream and a debris-depleted stream; g. an accumulatoroperatively connected to said air-solids separator and adapted toreceive said debris-enriched stream from said air-solids separator; saidair-solids separator and said accumulator having a baffle disposedbetween said air-solids separator and said accumulator for: i. generallyinhibiting secondary flow from said accumulator, and ii. impedingre-entrainment of fine particulates in said debris-depleted stream as itis discharged to the atmosphere; h. means operatively connected to saidblower unit and adapted to provide power to said blower unit; and i.means operatively connected to said collector rotor assembly and adaptedto provide power to said collector rotor.
 34. An apparatus forcollecting and reducing yard debris comprising: a. a frame adapted formovement in a principal direction upon a surface; b. a converging ductmounted on said frame having an entrance and an exit; c. a collectorrotor assembly comprising: a collector rotor body disposed at theentrance to said converging duct having a substantially horizontal axisof rotation generally normal to said first direction; and a plurality ofimpeller elements mounted upon said collector rotor body, said impellerelements being adapted to: i. engage and sweep over said surface, ii.collect yard debris thereupon, and iii. impel said yard debris towardsaid converging duct entrance, said impeller elements extending radiallyfrom said collector rotor body by at least about one quarter of an inch;said collector rotor assembly and said converging duct being configuredfor substantially untrammeled frontal engagement with yard debris havinga depth of at least about two (2) inches; d. a second duct having anentrance and an exit; e. a blower unit, disposed between said exit tosaid converging duct and said entrance to said second duct, adapted to:i. provide suction at said entrance of said converging duct, and ii.induce a flow of air through said converging and second ducts; f. anair-solids separator disposed at said exit to said second duct forseparating said yard debris in said flow of air induced by said blowerinto a debris-enriched stream and a debris-depleted stream; g. means fordischarging said debris-depleted stream to the atmosphere; h. anaccumulator operatively connected to said air-solids separator andadapted to receive said debris-enriched stream from said air-solidsseparator; i. means operatively connected to said blower unit andadapted to provide power to said blower unit; and j. means operativelyconnected to said collector rotor assembly and adapted to provide powerto said collector rotor assembly.
 35. The apparatus of claim 34 whereinsaid converging duct converges from said duct entrance to said ductexit.
 36. The apparatus of claim 34 wherein said entrance of saidconverging duct generally spans the collective width of said impellerelements.
 37. The apparatus of claim 34 wherein said converging duct hasgenerally equal cross-sectional area along its length.
 38. The apparatusof claim 34 wherein said air-solids separator comprises a free-flowapparatus for separating said yard debris from said flow of air byaction of body forces thereupon.
 39. An apparatus for collecting andreducing yard debris comprising: a. a frame adapted for movement in aprincipal direction upon a surface; b. a converging duct mounted on saidframe having an entrance and an exit; c. a second duct having anentrance and an exit; d. a blower unit, disposed between said exit tosaid converging duct and said entrance to said second duct, adapted to:i. provide suction at said entrance of said converging duct, and ii.induce a flow of air through said converging and second ducts, saidconverging duct having a convergence angle of less than about 120°; e. acollector rotor assembly comprising: a collector rotor body disposed atsaid entrance to said converging duct having a plurality of impellerelements mounted upon said collector rotor body, said impeller elementsbeing adapted to: i. engage and sweep over said surface, ii. collectyard debris thereupon, and iii. impel said yard debris toward saidentrance to said converging duct, said impeller elements extending fromsaid collector rotor body by at least about one quarter of an inch; saidcollector rotor assembly and said converging duct being configured forsubstantially untrammeled frontal engagement with yard debris having adepth of at least about two (2) inches; f. an air-solids separatordisposed at said exit to said second duct for separating said yarddebris in said flow of air induced by said blower into a debris-enrichedstream and a debris-depleted stream; g. means for discharging saiddebris-depleted stream to the atmosphere; h. an accumulator operativelyconnected to said air-solids separator and adapted to receive saiddebris-enriched stream from said air-solids separator; i. meansoperatively connected to said blower unit and adapted to provide powerto said blower unit; and j. means operatively connected to saidcollector rotor assembly and adapted to provide power to said collectorrotor assembly.